AU2019474270B2

AU2019474270B2 - Arrangement and method for recovering lithium hydroxide

Info

Publication number: AU2019474270B2
Application number: AU2019474270A
Authority: AU
Inventors: Sami KINNUNEN; Eero KOLEHMAINEN; Marika Tiihonen
Original assignee: Metso Finland Oy
Current assignee: Metso Finland Oy
Priority date: 2019-11-15
Filing date: 2019-11-15
Publication date: 2026-03-26
Anticipated expiration: 2039-11-15
Also published as: WO2021094647A1; BR112022009315A2; CN215439699U; CN112811445B; EP4058612A1; MX2022005783A; KR102901550B1; CA3160982A1; CN112811445A; KR20220098764A; AU2019474270A1; EP4058612A4

Abstract

The present invention relates to an arrangement and a method for recovering lithium hydroxide from a fresh feed comprising a mineral raw material containing lithium or a raw material containing lithium carbonate, or a mixture of these raw mate- rials,combined with a recycled solution and/or slurry containing lithium, by pulping the feed in the presence of water and alkali metal carbonate,leaching the obtained slurry twice, first at an elevated temperature, and secondly in an aqueous solution containing alkali earth metal hydroxide, separating the thus obtained slurry into solids that may be discarded,and a solution containing lithium hydroxide,whereby lithium hydroxide mono hydrate can be recovered from the solution by crystallising, and finally separating the solution and/or slurry obtained during the crystallization from the process and recycling it to one or more previous step, including the pulp- ing step,and optionally the first leaching step.

Description

ARRANGEMENT AND METHOD FOR RECOVERING LITHIUM HYDROXIDE

FIELD The present invention relates to an arrangement and a method for recov- 5 ering lithium hydroxide from lithium-containing mineral and lithium carbonate. 2019474270

BACKGROUND CN102115101 discloses a method for producing lithium carbonate from spodumene mineral by performing a sulfuric acid treatment in order to obtain lithium sulfate, followed by a step of preparing the lithium carbonate mother liquor, from 10 which the carbonate product can be separated, and finally the lithium hydroxide is obtained from the mother liquor by adding lime to causticize said mother liquor. Also, barium hydroxide is said to be useful as a causticizing hydroxide. CN 100455512 C discloses a process for preparing lithium hydroxide monohydrate by adding sodium hydroxide to a lithium sulfate solution in order to 15 obtain liquid lithium hydroxide, followed by cooling, filtering and separating the lith- ium hydroxide from the sodium sulfate, whereafter a series of recrystallization steps are performed to provide the pure lithium hydroxide monohydrate. In CN 1214981 C a similar process is described, wherein the step of add- ing sodium hydroxide into the lithium sulfate solution is carried out, followed by cool- 20 ing and separating to obtain the liquid lithium hydroxide. The lithium hydroxide so- lution is then concentrated and crystallized, whereby a coarse lithium hydroxide monohydrate product can be separated. In this publication the pure lithium hydrox- ide monohydrate is obtained by reacting the coarse product with barium hydroxide, followed by concentrating and crystallizing. 25 However, these processes all proceed via the lithium sulfate. US 3343910 A describes a method for recovering lithium hydroxide from a mineral raw material (calcined spodumene concentrate), by decomposing the min- eral using sodium carbonate at 200°C, leaching with calcium hydroxide at or near ambient temperature, and finally crystallizing the LiOH. It is further mentioned that 30 the usual practice for causticizing an isolated lithium carbonate is at about 85°C, or otherwise the results will be poor and uneconomical. US 334910 also describes that the hot mother liquor from the decomposition step, containing unspent sodium car- bonate may be removed in order to recycle the sodium carbonate. Optionally, the lithium compound can be separated from the leaching reaction product, and the 35 solution concentrated to the point of crystallization, whereafter the mother liquor may be returned to the process. However, no specific route for recycling is mentioned. Without further purification and recycling, the method is not very efficient.

Thus, there is still a need for procedures, which allow the use of mineral raw materials, and that will utilize the recycled streams containing or forming lithium carbonate, that in existing procedures will end up in the fractions that are discarded. 5 Any reference to prior art in the background above or elsewhere in this specification is not and should not be taken as an acknowledgment or any form of suggestion that the referenced prior art forms part of the common general 2019474270

knowledge in Australia or in any other country.

10 SUMMARY A preferred aim is to provide an arrangement and a method suitable for recovering lithium hydroxide from a feed comprising mineral raw material with high yield and high purity, typically of battery grade, without the need for multiple pro- cessing steps, including precipitation and purification steps, followed by further 15 needs for solid-liquid separations. Particularly, it is advantageous to provide an arrangement and a method for recovering lithium hydroxide using simple purification steps, and by optimising the recirculations. Battery grade lithium hydroxide herein means lithium hydroxide monohy- 20 drate crystals having a purity of 56.5%, or higher of lithium hydroxide. In addition, the process concept is sulphate and acid free, without the formation of undesired crystallized byproducts. This may be realised by an arrange- ment and a method which are characterized by what is stated in the independent claims. Preferred embodiments are disclosed in the dependent claims. 25 A disclosed embodiment relates to an arrangement for recovering lithium hydroxide from a fresh feed comprising a mineral raw material containing lithium or a raw material containing lithium carbonate, or a mixture of these, combined with a recycled solution and/or slurry, which arrangement comprises,

30 − a pulping unit 1 for pulping the feed in the presence of water and alkali metal carbonate, in order to form a first slurry containing lithium, − a first leaching unit 2 for leaching said first slurry containing lithium, op- tionally combined with a recycled solution and/or slurry, at an elevated temperature, in order to form a second slurry containing lithium car- 35 bonate, − a second leaching unit 3 for leaching said second slurry containing lith- ium carbonate, or a fraction thereof, in the presence of water and alkali

earth metal hydroxide, in order to form a third slurry containing lithium hydroxide, − a solid-liquid-separation unit 31 for separating said third slurry contain- ing lithium hydroxide into solids that may be discarded, and a solution 5 containing lithium hydroxide, and − a crystallising unit 4 for recovering lithium hydroxide monohydrate from a solution containing lithium. 2019474270

Said crystallization unit 4 is further connected to: one or more recycle lines 403,414,421,422 for carrying a solution and/or slurry from 10 the crystallizing unit 4 to one or more upstream units including the pulping unit 1, and optionally the first leaching unit 2.

According to a disclosed embodiment the arrangement comprises also further necessary lines for carrying solutions, solids or slurries to their intended units. 15 A disclosed embodiment also relates to a method for recovering lithium hydroxide from a fresh feed comprising mineral raw material containing lithium or a raw material containing lithium carbonate, or a mixture of these, combined with a recycled solution and/or slurry. The method comprises the following steps of 20 − pulping the feed in the presence of water and alkali metal carbonate for pro- ducing a first slurry containing lithium, − leaching the first slurry containing lithium, optionally combined with a recy- cled solution and/or slurry, in a first leaching step at an elevated tempera- ture for producing a second slurry containing lithium carbonate, 25 − leaching the second slurry or a fraction thereof in a second leaching step in an aqueous solution containing alkali earth metal hydroxide for producing a third slurry containing lithium hydroxide, − separating the third slurry into solids that may be discarded, and a solution containing lithium hydroxide by solid-liquid separation, 30 − recovering lithium hydroxide monohydrate by crystallising from a solution containing lithium hydroxide, and − separating the solution and/or slurry remaining after the crystallization from the process, and returning it as a recycled solution and/or slurry to one or more of the previous process steps including the pulping step, and option- 35 ally the first leaching step.

Typically, the mineral raw material containing lithium is selected from spodumene, petalite, lepidolite, micas or clays, or mixtures thereof, most suitably from spodumene. According to a disclosed embodiment the mineral raw material containing 5 lithium is selected from a mineral which has undergone heat treatment, whereby a particularly preferred material is beta-spodumene. According to an alternative disclosed embodiment, as stated above, a 2019474270

recycled solution and/or slurry can be used, containing lithium carbonate. Prefera- bly, said recycled solution and/or slurry is recycled from a downstream unit of the 10 arrangement. Most suitable, said recycled solution and/or slurry is used in combina- tion with fresh feed. According to a disclosed embodiment, the first leaching solution is sepa- rated from the solids after the first leaching step, whereby only the solids are carried to the second leaching step. 15 According to a disclosed embodiment, the first leaching solution is sepa- rated from the solids after the first leaching step and is returned as a recycled solu- tion either to the pulping step or to the first leaching step, or a fraction to each. According to a disclosed embodiment, a purifying step is carried out on the solution obtained from the solid/liquid separation step carried out after the sec- 20 ond leaching. According to a disclosed embodiment, the solution and/or slurry obtained from the crystallization step, or from an optional pre-concentration step, preferably carried out as an evaporation step, also called the bleed solution, is recovered and returned to one or more of the previous process steps including the pulping step, 25 and possibly also returned to the first leaching step, the second leaching step, and/or back to the crystallization step. Since a precipitate possibly forming already in the pre-concentration step would most likely be formed of, or at least contain, lithium carbonate, such a precip- itate-containing slurry would be highly suitable for recycling to said steps. 30 Optionally, the bleed solution obtained from the crystallization step is pre- treated prior to returning it to previous process steps, e.g. by carbonation, using CO2 to form a carbonate precipitate. When performing a first, optional, solid-liquid separation between the leaching steps, it is possible to recover the solution used in the first leaching step, 35 containing any excess of the leaching chemical, i.e. the alkali metal carbonate, and recycle it.

BRIEF DESCRIPTION OF THE DRAWINGS In the following the disclosed embodiments are described in greater de- tail with reference to Figures 1, 2, 3, 4, 5 and 6, which all show general flow diagrams and arrangements of units of certain embodiments.

5 DETAILED DESCRIPTION An embodiment, as presented schematically in Figure 1, is an arrange- 2019474270

ment for recovering lithium hydroxide from a fresh feed, combined with a recycled solution and/or slurry containing lithium, the arrangement of this particular embodi- ment including a pulping unit 1 for pulping the feed in the presence of water and 10 alkali metal carbonate, leaching the obtained slurry, optionally combined with a re- cycled slurry or solution, in a first leaching unit 2, followed by leaching in a second leaching unit 3, in the presence of water and alkali earth metal hydroxide, whereafter the obtained slurry is separated in a solid-liquid-separation unit 31 into solids that may be discarded, and a solution containing lithium hydroxide, whereby the solution 15 can be carried to a crystallization unit 4, for producing high purity lithium hydroxide. In the embodiment of Figure 1, the arrangement also includes recycle lines 421,422 for carrying a solution and/or slurry from the crystallization unit 4 to one or more upstream units, which in this embodiment include the pulping unit 1 and optionally the first leaching unit 2. However, also other recycling options are available, as in- 20 dicated in Figures 2 to 6 as well as in the claims. Further embodiments are illustrated in Figures 2 to 6. These specific em- bodiments are described in more detail below. The dotted lines in the drawings indicate that the units within these dotted lines can be combined in certain embodiments. 25 The feed containing lithium is typically selected from a fresh feed com- prising a mineral raw material containing lithium or a raw material containing lithium carbonate, or a mixture of these raw materials, combined with a recycled solution and/or slurry containing lithium. 30 Preferably, the mineral raw material is selected from spodumene, pet- alite, lepidolite, micas or clays or mixtures thereof. This mineral raw material is pref- erably a lithium-containing mineral in calcined form, more preferably obtained by heat treating the raw material, most suitably by using a temperature of 900-1200°C, particularly a temperature of 1000-1100°C. 35 A particularly preferred mineral is spodumene, providing beta-spodu- mene in a calcination step.

In a preferred embodiment, said mineral raw material is used in combi- nation with a slurry containing said lithium carbonate, preferably recycled from a subsequent step of the method.

5 Thus, the arrangement for recovering lithium hydroxide from a fresh feed comprising a mineral raw material containing lithium or a raw material containing lithium carbonate, or a mixture of these raw materials, combined with a recycled 2019474270

solution and/or slurry. The arrangement comprises − a pulping unit 1 for pulping the feed in the presence of water and alkali 10 metal carbonate, in order to form a first slurry containing lithium, − a first leaching unit 2 for leaching said first slurry containing lithium, op- tionally in combination with a recycled slurry or solution, at an elevated temperature, in order to form a second slurry containing lithium car- bonate, 15 − a second leaching unit 3 for leaching said second slurry containing lith- ium carbonate, or a fraction thereof, in the presence of water and an al- kali earth metal hydroxide, in order to form a third slurry containing lith- ium hydroxide, − a solid-liquid-separation unit 31 for separating said third slurry contain- 20 ing lithium hydroxide into solids that may be discarded, and a solution containing lithium hydroxide, − a crystallising unit 4 for recovering lithium hydroxide monohydrate from a solution containing lithium hydroxide, o which further comprises one or more recycle lines 25 403,414,421,422 for carrying a solution and/or slurry from the crystallizing unit 4 to one or more upstream units including the pulping unit 1 and optionally the first leaching unit 2.

The arrangement further comprises a calcination unit for heat treating the 30 raw material intended to be carried to the pulping unit 1. The pulping unit 1 preferably contains a feed inlet 101 for supplying the raw material containing lithium to the unit 1. The first leaching unit 2 is preferably an autoclave. In an embodiment, the first leaching unit 2 is connected to the pulping 35 unit 1 via a slurry line 102. Both the pulping unit 1 and the first leaching unit 2 may include separate inlets for carrying recycled solution, e.g. from recycle lines 211 and 421 to the pulp- ing unit 1 and from recycle lines 212 and 422, to the first leaching unit 2.

In an embodiment, a solid-liquid separation unit 21 is arranged between the first leaching unit 2 and the second leaching unit 3. Preferably, a recycle line 211,212 leads from the first leaching unit 2, or from the liquid section of a solid-liquid separation unit 21, to a unit upstream from 5 said first leaching unit 2. More preferably, said recycle line leads from the first leach- ing unit 2, or from the liquid section of a solid-liquid separation unit 21, either as line 211 to the pulping unit 1 or as line 212 to the first leaching unit 2, or as separate 2019474270

lines 211 and 212 to each. The second leaching unit 3 is a tank reactor, preferably a stirred tank 10 reactor. Preferably, the second leaching unit 3 includes an inlet 303 for alkali earth metal hydroxide or an aqueous slurry thereof. Optionally, the second leaching unit 3 may be connected to a slurrying unit 30 for mixing an alkali earth metal hydroxide into an aqueous slurry before car- 15 rying it via inlet 303 to the second leaching unit 3. Further, the second leaching unit 3 is typically connected to the first leaching unit 2, or to a downstream solid-liquid separation unit 21, via a slurry line 203. Typically, the solution or slurry obtained from the liquid section of the 20 solid-liquid separation unit 31 is carried via slurry line 304 to the crystallization unit 4 (see e.g. Fig. 3). Referring to Figs 4-6, a purification unit 32 is positioned between the solid-liquid separation unit 31 and the crystallization unit 4. This optional purification unit 32 is thus used in the purification of the solution separated from the third slurry. 25 The optional purification unit 32 preferably includes one or more of ion exchange units and membrane separation units, more preferably at least one or more ion ex- change units, most preferably cation exchange units, particularly containing a se- lective cation exchange resin. Thus, one option is to use a series of two or more ion exchange units, and possibly also a series of two or more regeneration units 33 30 In a preferred embodiment (see Fig. 5), where the purification unit 32 is an ion exchange unit, it is connected to a regeneration unit 33 for regenerating a purification resin. This regenerated resin can then be fed via a recycle line 332 back to the ion exchange unit 32. However, these purification and regeneration steps can also be carried out in a single unit 32 (see dotted line around units 32 and 33 of Fig. 35 5). No such regeneration is required when the purification unit 32 is a mem- brane separation unit. However, in the case a membrane separation unit is used, the unit provides two streams, one being a purified solution, which can be carried

directly to the crystallization unit 4, while the other is a recycle stream, which is suitable for carrying to the second leaching unit 3, for example via a recycle line 323 (see Fig. 6). In a further embodiment (see Fig. 6), the arrangement can include both 5 an ion exchange unit 32a and a membrane separation unit 32b, and thus also a regeneration unit 33. Due to the presence of the membrane separation unit 32b, a recycle stream can be provided, carrying a recycle stream via line 323 to the second 2019474270

leaching unit 3. In said embodiment it is particularly preferred to position the ion ex- 10 change unit 32a downstream from the membrane separation unit 32b. In an embodiment, the arrangement includes two or more crystallization units 4, preferably being sequentially arranged. Optionally, the crystallization unit(s) 4 can be preceded by a separate pre-concentration unit, preferably in the form of an evaporation unit, designed to 15 provide a crystallization feed having an optimized concentration. Typically, the arrangement comprises a solid-liquid separation unit 41 connected to the crystallization unit 4 for separating the crystals obtained in the crystallization unit 4 from the spent slurry. Further, as indicated above, one or more recycle lines 403,414,421,422 20 are arranged between the crystallizing unit 4, and/or the liquid section of the solid- liquid separation unit 41, and an upstream unit. These recycle lines may include recycle line 403 arranged between the crystallizing unit 4, or the liquid section of the solid-liquid separation unit 41, and the second leaching unit 3, recycle line 414 arranged between the crystallization unit 4, 25 or the liquid section of the solid-liquid separation unit 41, and an inlet of the crystal- lization unit 4, recycle line 421 arranged between the crystallization unit 4, or the liquid section of the solid-liquid separation unit 41, and the pulping unit 1, and recy- cle line 422 arranged between the crystallization unit 4, or the liquid section of the solid-liquid separation unit 41, and the first leaching unit 2. 30 Recycle line 403 is intended, among others, for carrying soluble alumin- ium back to the second leaching unit 3, after which it will form solid compounds that may be discarded. Recycle line 414, in turn, is intended for providing means of re- using, in the crystallization, as quickly as possible, the solution and/or slurry sepa- rated from the crystals obtained in the crystallization unit 4, i.e. the crystallization 35 mother liquor, which is a saturated solution that contains lithium hydroxide. Preferred alternatives, however, include recycle lines 421 and 422, of which recycle line 421 is particularly preferred. These lines are intended for recycling

and thus utilizing the lithium hydroxide that ends up in the mother liquor in the crys- tallization unit 4, while also preventing the build-up of other salts in the crystallization unit 4. In an embodiment, the arrangement comprises a lithium precipitation unit 5 42 connected to the crystallization unit 4 or the solid-liquid separation unit 41 through a line 423. One advantage of this precipitation unit 42 is that it provides means for 2019474270

reusing the solution recovered from the crystallization unit 4, which is a concentrated solution of a strong base, carrying a remarkable concentration of hydroxide ions. 10 This concentration of hydroxide ions is caused by the fact that lithium hydroxide crystallization can only be achieved from a saturated solution of lithium hydroxide, which is typically >12 % solutions, depending on selected temperature. On the other hand, the leaching units 2,3 are lower alkalinity environ- ments, with the first leaching unit 2 forming a sodium carbonate milieu, and the sec- 15 ond leaching unit 3 forming a milieu with a lower concentration lithium hydroxide solution; typically, about 2-3,5 %. Hence, large amounts of strong base should be avoided in the leaching units 2,3. As a consequence, neutralization of the major part of the hydroxide ions is needed. Carbonization provides suitable neutralization for the hydroxide ions, as 20 described below by referring to reaction formula (4). Preferably, the lithium precipitation unit 42 includes a feed inlet 424 for feeding carbon dioxide, and optionally alkali metal carbonate, to the unit 42. The precipitation reaction is, preferably not carried out completely, whereby the slurry recycled via the recycle lines 421a and/or 422a contains both 25 lithium carbonate and lithium hydroxide. The advantage of using such a slurry con- taining both lithium carbonate and lithium hydroxide has been explained above. For example, there is no need to make a complete conversion of hydroxide to carbonate in the precipitation unit 42, since some carbonation will occur also in the pulping unit 1 or the first leaching unit 2. 30 According to an embodiment, the recycle lines 421 and/or 422 may be connected to this precipitation unit 42, instead of being connected directly to the crystallization unit 4, or the liquid section of the solid-liquid separation unit 41, as recycle lines 421a and/or 422a. According to another embodiment, separate lines 421 and 421a as well 35 as separate lines 422 and 422a are provided, and there is no requirement to com- bine these recycled slurries and/or solutions before leading them to the pulping unit 1 or first leaching unit 2, respectively.

It is particularly preferred to lead recycle line 421 past the precipitation unit 42, since carbonation will take place also in the pulping unit 1, to which the recycle line 421 will lead. Since the lithium hydroxide solution is a concentrated solution of a strong 5 base, it provides a highly suitable solution to be used to control the pH in the first leaching unit 2, which control is necessary in order to maintain suitable leaching conditions. When this solution is brought into contact with the sodium carbonate 2019474270

solutions for example in the pulping step, some sparingly soluble lithium carbonate will simultaneously precipitate, as described below, by referring to reaction formula 10 (3). This reaction provides lithium carbonate for further lithium hydroxide recovery and sodium hydroxide for pH control. Thus, one specific feature is that it provides the means for supplying lith- ium carbonate already in line 102, leading to the first leaching unit 2, instead of forming the lithium carbonate only in the first leaching unit 2. 15 In an embodiment, the arrangement includes a purification unit 43 con- nected to the crystallization unit 4, and/or to the solid-liquid separation unit 41, wherein the solids obtained in the crystallization step can be purified. Preferably, the purification unit 43 includes a feed inlet 431 for feeding a washing solution into the purification unit 43. 20 In an embodiment, the arrangement includes a solid-liquid separation unit 44 connected to and downstream from the purification unit 43, for separating the purified crystals of lithium hydroxide monohydrate from the spent washing solu- tion. Preferably, the purification unit 43, or a solid-liquid separation unit 44, 25 connected to and downstream from the purification unit 43 is connected via a recycle line 432 to an upstream purification unit 32, or to a regeneration unit 33. More preferably, a solid-liquid separation unit 44 connected to and down- stream from the purification unit 43 is connected via a recycle line 444 to the crys- tallization unit 4. 30 Even more preferably, a solid-liquid separation unit 44 connected to and downstream from the purification unit 43 is connected via a recycle line 445 to the purification unit 43. In another option, the arrangement comprises a combined purification unit 41,43,44 for purifying the crystals obtained in the crystallization unit 4 from the 35 spent solution, and separating the purified crystals from the spent washing solution. In this alternative option, the recycle line 414 connects the combined unit 41,43,44 to the crystallization unit. Likewise, the feed inlet 431 is connected to the combined purification unit 41,43,44. Further, a recycle line 432 may connect the

combined purification unit 41,43,44 to an upstream purification unit 32, or to a sep- arate regeneration unit 33, and a recycle line 444 may connect the combined purifi- cation unit 41,43,44 to the crystallization unit 4. Finally, a recycle line 445 may connect a solids section of the combined purification unit 41,43,44 to the liquid sec- 5 tion of the same combined unit 41,43,44. In an embodiment, the arrangement includes a drying unit 45, connected to the crystallization unit 4, or connected to a solids section of a solid-liquid separa- 2019474270

tion unit 41,44 downstream from the crystallization unit 4, wherein the obtained crys- tals of lithium hydroxide monohydrate can be dried. 10 Preferably, the drying unit 45 includes a product outlet 451 through which the final, battery grade, product can be recovered.

Disclosed embodiments also include a method for recovering lithium hy- droxide from a fresh feed comprising mineral raw material containing lithium, or a 15 raw material containing lithium carbonate, or a mixture of these, combined with a recycled solution and/or slurry containing lithium. The method comprises (by referring to the numbering used for the ar- rangement) pulping 1 the feed containing lithium in the presence of water and alkali metal carbonate for extracting the lithium from the feed and producing a first slurry 20 containing lithium. The alkali metal carbonate is preferably selected from sodium and potas- sium carbonate, most suitably being at least partly composed of sodium carbonate. Typically, the alkali metal carbonate is present in excess. After pulping, the first lithium-containing slurry, optionally in combination 25 with a recycled slurry or solution, is leached 2 for a first time at an elevated temper- ature, for producing a second slurry containing lithium carbonate. The presence of alkali metal carbonate and process conditions result in the formation of lithium carbonate and analcime solids, which can be presented in the case of spodumene and sodium carbonate with the following formula (1). 30 2 LiAl(SiO3)2 + Na2CO3 = 2NaAl(SiO3)2 + Li2CO3 (1)

The first leaching 2 of the first slurry containing lithium is typically per- formed in a suitable autoclave or series of autoclaves. 35 In an embodiment, the first leaching step is carried out at a temperature of 160 to 250°C, preferably at a temperature of 200 to 220°C. Likewise, the first leaching step is preferably carried out at a pressure of 10 to 30bar, preferably 15 to

25bar. Suitable conditions for this step are typically achieved using high-pressure steam. Preferably, at least a fraction of the water and alkali metal carbonate car- ried to the pulping step is obtained from a recycled aqueous solution containing said 5 alkali metal carbonate, and optionally containing lithium carbonate. An optional solid-liquid separation step 21 can be carried out, wherein the solution can be separated from the solids after the first leaching step 2, and the 2019474270

solids carried to the second leaching step 3. In an embodiment, the solution separated from the solids in the optional 10 separation step 21 is returned to one or more of the preceding steps as a recycled solution. Preferably, the solution is returned either to the pulping step or to the first leaching step, or a fraction to each. More preferably, the solution is returned to the pulping step. 15 In the second leaching step 3, the lithium-containing phase (here typically the solids, or the entire second slurry) is leached 3 for a second time using a hy- droxide reagent, i.e. an alkaline earth metal hydroxide, preferably in an aqueous solution of the hydroxide reagent, in order to form a third slurry containing lithium hydroxide. Subsequently, a separation of solids from the solution is carried out by 20 solid-liquid separation 31. This separation 31 results in the formation of a solids fraction that may be discarded, and a solution containing lithium hydroxide. The alkali earth metal hydroxide used in the second leaching step 3 is preferably selected from calcium and barium hydroxide, more preferably being cal- cium hydroxide, optionally prepared by reaction of calcium oxide (CaO) in the aque- 25 ous solution. In an embodiment, the alkali earth metal hydroxide used in the second leaching step 3 is mixed with water or an aqueous solution prior to addition to the second leaching step 3. The hydroxide reagent may, for example, be obtained from a separate slurrying step 30. 30 Preferably, at least a fraction of the solution separated from the solids in separation step 31, containing among others lithium and sodium, is added to said second leaching step in the form of a recycled solution, preferably mixed with fresh alkali earth metal hydroxide prior to addition to the second leaching step, more pref- erably mixed with fresh alkali earth metal hydroxide in a separate slurrying step 30. 35 The second leaching step 3 is typically carried out at a temperature of 10-100°C, preferably 20-60°C, and most suitably 20-40°C. Typically, the second leaching step 3 is carried out at atmospheric pressure.

The presence of alkaline earth metal hydroxide and process conditions result in the formation of lithium hydroxide, which can be presented in the case of analcime, lithium carbonate and calcium hydroxide with the following formula (2).

5 2NaAl(SiO3)2 + Li2CO3 + Ca(OH)2= 2NaAl(SiO3)2 + CaCO3 + 2LiOH (2)

All the lithium carbonate reacts in this second leaching step 3 in said 2019474270

conditions. This includes the lithium carbonate formed in the first leaching step 2, in reaction (1), i.e. in high pressure conditions, and the lithium carbonate precipitated 10 in the below described reactions (3) and (4), as well as lithium carbonate added as the fresh feed. After the two leaching steps 2,3 have been performed, the obtained third slurry containing lithium hydroxide is separated 31 into a solid phase and a solution. The solution contains at least the main part of the formed lithium hydroxide, whereby 15 the solid phase may be discarded. The separation 31 can be done with any suitable solid-liquid separation method. For example, the third slurry can be routed to a thick- ener, from where the overflow can be routed directly to purification and the under- flow can be filtered further in order to recover all lithium hydroxide present in the solution and separate it from solid impurities, or a simple filtering technique can be 20 used. Typically, all solid-liquid separations described herein require a supply of washing water for washing of the solids (as shown in Figures 3-6). One reason for this optional solids-washing step is to displace a further fraction of the solution that is accompanying the solids as moisture. After washing, the spent washing water is typically returned to a preceding step of the method as a recycle solution. If the used 25 washing water is recycled, this washing step will also provide the further benefit of recovery of useful reagents. The solids obtained from this separation of the third slurry into solids and a solution are typically composed of unwanted residues, which can be discarded, e.g. as tailings. 30 According to an embodiment, the third slurry separated from the second leaching step 3 is purified 32 before carrying it to the crystallization step. This op- tional purification step is preferably based on purification of dissolved ions and com- ponents, and more preferably includes ion exchange or a membrane separation steps, or both, most suitably by using a cation exchange resin, particularly a selec- 35 tive cation exchange resin. Typically, the purifying by ion exchange is performed by using cation ex- change resin, wherein the cation exchange group is for example iminodiacetic acid (IDA) or aminophosphonic acid (APA).

Selective cation exchange resins typically have a chelating functional group attached to the resin matrix. These chelating functional groups usually have a much higher selectivity towards multi-valent metal cations, such as heavy and alkaline earth metal cations, compared to the monovalent alkali metal cations (Li, 5 Na, K). Suitable resin functionalities are, for example the above mentioned iminodi- acetate and the aminophosphonate. These chelating resins can be used to purify the typical cationic impurities, such as calcium ions (Ca2+) from lithium hydroxide 2019474270

solutions. In an embodiment, the step of purifying the solution obtained from the 10 third slurry is carried out at least partly using a resin that has been regenerated in a separate regeneration step. Preferably, the regeneration step is carried out using a recycled solution from a subsequent process step, more preferably being the separated solution ob- tained during the crystallization, optionally in purified form. 15 In a preferred embodiment, this regeneration is carried out using at least acidic solution for metal elution, preferably being hydrochloric acid (HCl), and an alkaline solution for neutralization, preferably being sodium hydroxide (NaOH) or an alkaline lithium hydroxide solution, more preferably a recycled solution containing lithium hydroxide. Further, water can be fed to the regeneration step. The regener- 20 ated resin can be fed back to the ion exchange. These purification and regeneration steps can, however, also be com- bined, and carried out in the same purification unit. According to another option, the purification step can be performed in a unit 32 that includes a series of two or more ion exchange units. Likewise, a series 25 of two or more regeneration units 33 may be used. The membrane separation can be carried out using a semi-permeable membrane, which separates ionic or other dissolved compounds from aqueous so- lutions. More precisely, the membrane separation can be used to fractionate the dissolved ions and compounds by their size (depending on the pore size of the 30 membrane material), and/or their charge (depending on the surface charge of the membrane material). A positive surface charge repels cations (with a stronger re- pelling action for multi-valent cations) and attracts anions, and vice versa. These phenomena will enable the purification of, for example, multi-valent metal cations, complexed species (such as aluminium hydroxide complexes), polymeric species 35 (such as dissolved silica) and larger anions (e.g. sulfate and carbonate ions) from lithium hydroxide solutions. With the membrane separation, no regeneration is re- quired.

Since lithium hydroxide is a strong alkali having a high concentration of hydroxide ions, metals that are strongly complexed by hydroxide ions (such as alu- minium ions, Al3+) cannot be purified by the above-mentioned selective cation ex- change resins. Therefore, these ions are purified using the herein described recir- 5 culations. The selective cation exchange is preferably used in the polishing removal of multivalent metal cations that form sparingly soluble hydroxide compounds (typi- 2019474270

cally calcium hydroxide). These metals (or metal cations) should be removed, or at least their concentrations should be reduced to very low levels in the solution to be 10 carried to the crystallization, in order to prevent them from contaminating the crys- tallized lithium hydroxide monohydrate product. The removal of these metals is not as efficient with membranes, and is thus preferably done by ion exchange, particu- larly with a selective cation exchange resin. In case a membrane separation is carried out, either alone or combined 15 with an ion exchange, a recycle stream is provided from the membrane separation, which is suitable for carrying to the second leaching step 3. In membrane separation, the retained ions and compounds will end up in a concentrated fraction, typically called the “retentate”, which can be returned to the second leaching step as a recycled fraction as described above. The other obtained 20 fraction is the permeated liquid fraction, i.e. the “permeate”, which is fed to the crys- tallization, optionally via the ion exchange purification, if these purifications are com- bined. The fraction to which each ion and compound ends up in the membrane separation depends on their characteristics: for example, their charge and size. This 25 targeting of the retention can be done based on selection of the desired membrane type, based on surface charge and/or pore size. For the charge, the targeted retained species would typically be multi- valent metal cations, for example: calcium ions (Ca2+), magnesium ions (Mg2+) vs. permeated (or zero to negatively retained) monovalent alkali metal cations, such as 30 lithium ions (Li+) or sodium ions (Na+). For the size, the retained species would typically be larger compounds, for example: polymeric species (such as dissolved silica), complexed ions (such as aluminium hydroxide complexes), and the largest types of anions (such as car- bonate,CO32-, and sulfate, SO42-), whereas the smallest types of anions (such as 35 hydroxide, OH-), are permeated (or: has zero or negative retention). Based on the above, it is particularly preferred to combine a membrane separation with an ion exchange, most suitably by first carrying out a membrane

separation, and then an ion exchange for polishing removal of multivalent metal cations. In the final steps of the method, crystals of lithium hydroxide monohydrate are recovered by crystallising 4 from a lithium-containing solution, which has option- 5 ally been purified. The crystallizing is typically performed by heating the solution containing lithium to a temperature of approximately the boiling point of the solution, to evaporate the liquid, or by recrystallizing the monohydrate from a suitable solvent. 2019474270

Optionally, a pre-concentration can be carried out before the crystalliza- tion step, preferably as an evaporation. 10 In an embodiment, two or more crystallization units are used, preferably being sequentially arranged. The method enables production of pure lithium hydroxide monohydrate with excellent yield and purity in a continuous and simple process, typically providing battery grade lithium hydroxide monohydrate crystals, having a purity of 56.5% or 15 higher of lithium hydroxide. In another embodiment, the purified solution containing lithium hydroxide is mixed with one or more solutions recycled from subsequent steps of the method before being carried to the crystallization step 4, or these solutions can be fed sep- arately to the crystallization 4. 20 Preferably, the crystallization step 4 is followed by a solid-liquid separa- tion step 41. The bleed solution obtained while crystallizing 4 the lithium hydroxide monohydrate can be recovered and is recycled to one or more of the previous pro- cess steps, including the pulping step 1, and optionally also the first leaching step, 25 the second leaching step 3, and/or back to the crystallization step 4. It is particularly preferred to recycle at least a fraction of the solution sep- arated from the crystallization step to at least the pulping step 1 and the first leaching step 2. The solution separated from the crystallization step is a saturated solu- 30 tion that contains a remarkable concentration of lithium hydroxide, which should be recovered. Further, it is a concentrated solution of a strong base. Hence, it provides a highly suitable solution to be used to control the pH in the first leaching unit 2. Due to the recycling streams carried to the pulping step 1 and the first leaching step 2, the main one being the stream carried to the pulping step via recycle line 211, this 35 pH control is necessary. When this lithium hydroxide solution is brought into contact with the sodium carbonate solutions for example in the pulping step, some sparingly soluble lithium carbonate will simultaneously precipitate, as presented in the follow- ing formula (3):

LiOH(aq) + Na2CO3(aq) = Li2CO3(s) + NaOH (aq) (3)

This reaction provides lithium carbonate for further lithium hydroxide re- 5 covery and sodium hydroxide for pH control. Further, some impurities in the crystallization bleed solution (e.g. alumin- ium and silicon) have a solubility that increases with increasing alkalinity (e.g. 2019474270

caused by increasing lithium hydroxide concentration), whereby these alkali-soluble impurities can be removed by returning them in solution to a step of lower alkalinity, 10 such as the pulping or first leaching steps. In said lower alkalinity environment, these impurities form sparingly soluble compounds (e.g. aluminium hydroxide), and can be discarded with the solids in separation step 31. Also carbonate ions can be re- covered and utilized in this manner. In an embodiment, a fraction of the solution separated from the crystalli- 15 zation step is returned to the second leaching step as a recycle solution. The advantage of these recycling options is that the soluble impurities remaining in the liquids after crystallization (main impurities being sodium, potas- sium, aluminium and carbonate ions, as well as soluble silicon and silicates) can be circulated upstream, where they can be removed. Particularly in the leaching steps, 20 these impurities form sparingly soluble compounds, which can be discarded as sol- ids after the second leaching step. Without the herein mentioned recycling options, these impurities would be concentrated in the crystallization step, and contaminated in the product. In another embodiment, a fraction of the solution separated from the crys- 25 tallization step is returned to the crystallization step as a recycle solution. In a typical crystallization process, the crystallization slurry is maintained in a continuous circu- lation, from which product crystals are continuously separated, and the advantage of recycling at least a fraction of the remaining mother liquid is that it increases the yield of the process. 30 In a further embodiment, at least a fraction of the solution separated from the crystallization step is carried to a lithium precipitation step 42, which preferably is carried out as a carbonation, wherein the solution is reacted with either carbon dioxide or an alkali metal carbonate, or both, preferably at least with carbon dioxide, in order to form a lithium carbonate slurry, as presented in the following formula (4) 35 2LiOH + CO2 = Li2CO3 + H2O (4)

This optional lithium precipitation step 42 has the advantage of reacting lithium hydroxide contained in the crystallization bleed solution into the correspond- ing carbonate, which is highly suitable for returning as a recycle solution to the pulp- ing step 1 or the first leaching step 2 of the method. 5 Lithium hydroxide crystallization can only be achieved from a saturated solution of lithium hydroxide, which is typically >12 % solutions, depending on se- lected temperature. Thus, the solution recovered from the crystallization step pro- 2019474270

vides a concentrated solution of a strong base carrying a remarkable concentration of hydroxide ions. On the other hand, the leaching steps (first and second) are lower 10 alkalinity environments. The first leaching step is carried out in a sodium carbonate milieu, and the second leaching step is carried out on a lower concentration lithium hydroxide solution; typically, about 2-3,5 %. Hence, there is very little need for a strong base in the leaching steps. As a consequence, neutralization of the major part of the hydroxide ions is needed, and carbonization provides such a suitable 15 neutralization. When using this optional precipitation step, the solution returned from the crystallization step 4 to the pulping step 1 and optionally the first leaching step 2 can be carried via this precipitation step, where, among others, lithium hydroxide is con- verted into lithium carbonate. The reaction can, however, be left incomplete, 20 whereby at least a trace amount of lithium hydroxide will still be present in the lithium carbonate slurry to be recycled. As mentioned above, some conversion of the lithium hydroxide to the corresponding carbonate will occur also in the pulping step, whereby a complete carbonation in the precipitation step is unnecessary. However, also some carbonate is useful in these steps. 25 Regardless of whether the precipitation step is used or not, the solution and/or slurry returned from the crystallization step to the pulping step and optionally the first leaching step will thus contain some lithium hydroxide. This lithium hydrox- ide will, however, typically be converted to the corresponding sparingly soluble car- bonate in the pulping or first leaching step. 30 In an embodiment, the solids obtained in the crystallization step, contain- ing crystals of lithium hydroxide monohydrate, are purified using a washing solution before recovery as the product. The purified crystals of lithium hydroxide monohydrate are preferably separated from the washing solution, are dried, and thereafter recovered. 35 The spent washing solution is, in turn, preferably separated from the pu- rified crystals of lithium hydroxide monohydrate, and is returned to the crystal wash-

ing step or to a step of regenerating a resin intended for being carried to the purifi- cation step, or to the crystallization step, or a fraction of the spent washing solution is returned to two or all three of these steps as a recycle solution. It is particularly preferred to return at least a fraction of this spent washing 5 solution (or crystallization mother liquid) to the regeneration step, since the solution is relatively pure and contains uncrystallized lithium hydroxide, which should be re- used, particularly in a step upstream from the crystallization, or in the crystallization. 2019474270

Thus, the regeneration 33 is an option for the recycling.

10 REFERENCE NUMBERS

The reference numbers according to disclosed embodiments, as used in Figures 1 to 6, are shown below (some of these units and lines being optional):

15 1 pulping unit 101 feed inlet for supplying fresh feed to the pulping unit 1 102 slurry line for carrying a first slurry from the pulping unit 1 to the first leaching unit 2 2 first leaching unit 20 203 slurry line for carrying a second slurry from the first leaching unit 2 to the second leaching unit 3 21 solid-liquid separation unit 211 recycle line from separation unit 21 to pulping unit 1 212 recycle line from separation unit 21 to first leaching unit 2 25 3 second leaching unit 30 slurrying unit for mixing an alkali earth metal hydroxide into an aqueous slurry 303 inlet for supplying alkali earth metal hydroxide or an aque- ous solution thereof to the second leaching unit 3 30 304 liquid line for carrying a third slurry from the second leach- ing unit 3, or from the separation unit 31, either directly to the crystallization unit 4, or to the purification unit 32 or the optional regeneration unit 33 31 solid-liquid separation unit 35 313 recycle line for carrying a solution obtained from the sep- aration unit 31 to the second leaching unit 3, or to the op- tional slurrying unit 30

32 purification unit downstream from the S/L separation unit 31, and upstream from the crystallization unit 4 323 recycle line for carrying a recycle stream from the purifica- tion unit 32 to the second leaching unit 3 5 33 regeneration unit 332 recycle line for carrying a regenerated stream from the re- generation unit 33 to the purification unit 32 2019474270

4 crystallizing unit 403 recycle line from crystallizing unit 4, or the separation unit 10 41, to the second leaching unit 3 41 solid-liquid separation unit 414 recycle line from a downstream point of the crystallization unit 4, or from the separation unit 41, back to the crystal- lizing unit 4 15 42 lithium precipitation unit 421 recycle line from the crystallization unit 4, optionally via the separation unit 41 or the precipitation unit 42, to the pulp- ing unit 1 421a recycle line from the crystallization unit 4, via the precipi- 20 tation unit 42, to the pulping unit 1 422 recycle line from the crystallization unit 4, optionally via the separation unit 41 or the precipitation unit 42, to the first leaching unit 2 422a recycle line from the crystallization unit 4, via the precipi- 25 tation unit 42, to the first leaching unit 2 423 slurry line for carrying a reacted slurry from the crystalliza- tion unit 4, or the separation unit 41, to the lithium precipi- tation unit 42 424 feed inlet for supplying carbon dioxide or an alkali metal 30 carbonate to the precipitation unit 42 43 purification or washing unit 431 feed inlet for supplying washing solution to the purification or washing unit 43 432 recycle line for carrying spent washing solution to the up- 35 stream purification unit 32, or to an optional regeneration unit 33 44 solid-liquid separation unit

444 recycle line for carrying spent solution from purification unit 43 or the separation unit 44 to the crystallization unit 4 445 recycle line for carrying spent solution from purification 5 unit 43 or the separation unit 44 to the purification or wash- ing unit 43 45 drying unit 2019474270

451 product outlet for crystallized and optionally purified and dried lithium hydroxide monohydrate 10 In this specification, the term ‘comprising’ is intended to denote the inclu- sion of a stated integer or integers, but not necessarily the exclusion of any other integer, depending on the context in which that term is used. This applies also to variants of that term such as ‘comprise’ or ‘comprises’. 15 It will be obvious to a person skilled in the art that, as the technology advances, the inventive concept can be implemented in various ways. The invention and its embodiments are not limited to the examples described above but may vary within the scope of the claims.

20 EXAMPLES

EXAMPLE 1 A batch test for leaching and recycling was carried out by adding solid lithium carbonate to a beta-spodumene slurry, and treating the obtained mixture in an autoclave leaching step, followed by a second leaching step, as follows: 25 A 700g batch of calcined beta-spodumene material with a 3.0% Li con- tent, 178g of sodium carbonate and an additional 7g of solid lithium carbonate were mixed with water to form a slurry having a total volume of 2.8 liters. The slurry was added to a 1-gal autoclave and treated for two hours at 220°C. The autoclave con- tents were allowed to cool and then the slurry was filtered. A 225.93g portion of the 30 pressure leach cake and 25g of calcium oxide were slurried with 0.63l of deionized water and mixed to make up a slurry of total volume 0.75l. The slurry was treated for 1h at ambient temperature and finally solids and a liquid were separated by fil- tration, and the cake was washed with water. The contents of both the solids and the solution were analyzed. The solids residue contained 0.16% Li and the solution 35 had a Li content of 6.7g/l. The contents of the solution are specified in the following Table 1.

The lithium recovery/yield to the solution was excellent, at around 93%, whereby recycling of this solution to an early step of the process is highly beneficial. It was also clear based on these results that a further purification step, e.g. by ion exchange, can be included in the procedure, particularly to remove im- 5 purity metals, such as calcium.

Table 1. Solution intended for product LiOH • H2O crystallization Li B Na Mg Al Si P S ICP K ICP Ca ICP Mn ICP Fe ICP Zn C Sample mg/l mg/l mg/l mg/l mg/l mg/l mg/l mg/l mg/l mg/l mg/l mg/l mg/l mg/l Solu- 6720 <3 175 <2 9 32 <30 <20 52 20 <1 <2 <3 225 tion

Claims

CLAIMS 26 Feb 2026

1. An arrangement for recovering lithium hydroxide from a fresh feed comprising a mineral raw material containing lithium or a raw material containing lithium car- 5 bonate, or a mixture of these raw materials, combined with a recycled solution and/or slurry containing lithium, which arrangement comprises − a pulping unit for pulping the feed in the presence of water and alkali metal carbonate, in order to form a first slurry containing lithium, 2019474270

− a first leaching unit for leaching said first slurry containing lithium, op- 10 tionally combined with a recycled solution and/or slurry, at an elevated temperature, in order to form a second slurry containing lithium car- bonate, − a second leaching unit for leaching said second slurry containing lithium carbonate, or a fraction thereof, in the presence of water and alkali earth 15 metal hydroxide, in order to form a third slurry containing lithium hydrox- ide, − a solid-liquid-separation unit for separating said third slurry containing lithium hydroxide into solids that may be discarded, and a solution con- taining lithium hydroxide, 20 a crystallising unit for recovering lithium hydroxide monohydrate from a solution containing lithium hydroxide, which further comprises o a solid-liquid separation unit, connected to the crystallization unit, and o one or more recycle lines for carrying a solution and/or slurry 25 from the crystallization unit to one or more upstream units includ- ing the pulping unit and optionally the first leaching unit, and − a lithium precipitation unit connected to the liquid section of the solid liq- uid separation unit, connected to the crystallization unit, through a line, o whereby the one or more recycle lines are arranged between said 30 lithium precipitation unit and one or more of the pulping unit and the first leaching unit.

2. The arrangement according to claim 1, which further comprises a calcination unit for heat treating the mineral raw material intended to be carried as at least a part of 35 the feed to the pulping unit.

3. The arrangement according to any preceding claim, wherein the first leaching unit is an autoclave.

4. The arrangement according to any preceding claim, wherein the first leaching unit is connected to the pulping unit via a slurry line.

5 5. The arrangement according to any preceding claim, wherein a solid-liquid sepa- ration unit is arranged between the first leaching unit and the second leaching unit, and optionally a washing unit, or a washing section within the separation unit, for washing the solids separated from the liquid in the separation unit. 2019474270

10 6. The arrangement according to any one of claims 1 to 5, which includes a recycle line leading from the first leaching unit, or from the liquid section of a solid-liquid separation unit connected to said first leaching unit, to a unit upstream from said first leaching unit.

15 7. The arrangement according to any one of claims 1 to 5, which includes a recycle line leading from the first leaching unit, or from the liquid section of a solid-liquid separation unit placed in connection with said first leaching unit, either as line to the pulping unit or as line to the first leaching unit, or a separate line and to each.

20 8. The arrangement according to any one of claims 1 to 5, which includes a recycle line leading from the first leaching unit, or from the liquid section of a solid-liquid separation unit connected to said first leaching unit, to the pulping unit.

9. The arrangement according to any preceding claim, wherein the second leaching 25 unit is a tank reactor, preferably a stirred tank reactor.

10. The arrangement according to any preceding claim, wherein the second leach- ing unit includes an inlet for alkali earth metal hydroxide or an aqueous slurry thereof. 30 11. The arrangement according to any one of claims 1 to 9, wherein the second leaching unit is connected to a slurrying unit for mixing an alkali earth metal hydrox- ide into an aqueous slurry.

35 12. The arrangement according to any preceding claim, wherein the second leach- ing unit is connected to the first leaching unit, or to a downstream solid-liquid sepa- ration unit, via a slurry line.

13. The arrangement according to any preceding claim, wherein the solid-liquid sep- 26 Feb 2026

aration unit, positioned downstream from the second leaching unit, is connected to a washing unit, or includes a washing section within the separation unit, for washing the solids separated from the liquid in the separation unit. 5 14. The arrangement according to any preceding claim, which includes a purification unit connected to the solid-liquid-separation unit, for purifying the solution obtained from said separation unit. 2019474270

10 15. The arrangement according to claim 14, wherein the purification unit includes one or more of ion exchange units and membrane separation units, preferably at least one or more ion exchange units, more preferably cation exchange units, par- ticularly containing a selective cation exchange resin.

15 16. The arrangement according to claim 14, wherein the purification unit is an ion exchange unit, or a series of two or more ion exchange units, and is connected to a regeneration unit, or a series of two or more regeneration units, for regenerating a purification resin, and wherein a line is typically connected between the purification unit and the regeneration unit, for returning regenerated resin back to the ion ex- 20 change unit.

17. The arrangement according to claim 14, wherein the purification unit is a mem- brane separation unit, which is connected both to the crystallization unit, by feeding the crystallization unit with purified solution, and to the second leaching unit, via 25 recycle line, for returning a recycle stream to the leaching step.

18. The arrangement according to claim 14, wherein the purification unit is a com- bination of a membrane separation unit and an ion exchange unit, wherein the mem- brane separation unit has an outlet that is connected to an inlet of the ion exchange 30 unit.

19. The arrangement according to any preceding claim, which includes two or more crystallization units, preferably being sequentially arranged.

35 20. The arrangement according to any preceding claim, wherein the crystallization unit, or a downstream purification unit or a downstream regeneration unit, is con- nected to the solid-liquid separation unit positioned downstream from the second leaching unit via liquid line.

21. The arrangement according to any preceding claim, wherein the crystallization unit is preceded by pre-concentration unit, preferably in the form of an evaporation unit, designed to provide a crystallization feed having an optimized concentration. 5 22. The arrangement according to any preceding claim, which comprises said solid- liquid separation unit connected to the crystallization unit for separating the crystals obtained in the crystallization unit from the spent solution. 2019474270

10 23. The arrangement according to any preceding claim, which comprises a recycle line arranged between the crystallizing unit, and/or the liquid section of the solid- liquid separation unit connected to the crystallization unit, and the second leaching unit.

15 24. The arrangement according to any preceding claim, wherein the lithium precipi- tation unit includes a feed inlet for feeding carbon dioxide or an alkali metal car- bonate, or a mixture of these, to the unit.

25. The arrangement according to claim 22 or claim 23, wherein the liquid section 20 of the solid-liquid separation unit is connected to the crystallization unit, optionally via the crystallization feed, via recycle line, for recycling a fraction of the spent solu- tion separated from the crystallization step back to the crystallization unit.

26. The arrangement according to any preceding claim, which includes a product 25 purification unit connected to the crystallization unit, and/or to a solid-liquid separa- tion unit connected to the crystallization unit, wherein the solids obtained in the crys- tallization step can be purified.

27. The arrangement according to claim 26, wherein the product purification unit 30 includes a feed inlet for feeding a washing solution into the product purification unit, preferably being connected to a recycle line, such as recycle line.

28. The arrangement according to claim 26 or claim 27, which includes a solid-liquid separation unit connected to and downstream from the product purification unit, for 35 separating the purified crystals of lithium hydroxide monohydrate from the spent washing solution.

29. The arrangement according to any one of claims 26 to 28, wherein the product 26 Feb 2026

purification unit, or a solid-liquid separation unit connected to and downstream from the product purification unit is connected via a recycle line to the upstream purifica- tion unit or to an optional regeneration unit connected to said upstream purification 5 unit.

30. The arrangement according to any one of claims 26 to 28, wherein a solid-liquid separation unit connected to and downstream from the product purification unit is 2019474270

connected via a recycle line to the crystallization unit. 10 31. The arrangement according to any one of claims 26 to 28, wherein a solid-liquid separation unit connected to and downstream from the product purification unit is connected via a recycle line to the product purification unit.

15 32. The arrangement according to any one of claims 1 to 19, which comprises a combined product purification unit for purifying the crystals obtained in the crystalli- zation unit from the spent solution, and separating the purified crystals from the spent washing solution.

20 33. The arrangement according to claim 32, wherein the combined product purifica- tion unit is connected to the crystallization unit via recycle line, for returning the spent solution separated from the crystallization step back to the crystallization unit as a recycled solution.

25 34. The arrangement according to claim 32, wherein the combined product purifica- tion unit includes a feed inlet for feeding a washing solution into the unit.

35. The arrangement according to claim 32, wherein the combined product purifica- tion unit is connected via a recycle line to the upstream purification unit, or to a 30 separate regeneration unit.

36. The arrangement according to claim 32, wherein the combined product purifica- tion unit is connected via a recycle line to the crystallization unit.

35 37. The arrangement according to claim 32, wherein a solids section of the com- bined product purification unit is connected via a recycle line to the liquid section of the same combined unit.

38. The arrangement according to any preceding claim, which includes a drying unit, 26 Feb 2026

connected to the crystallization unit, or connected to a solids section of a solid-liquid separation unit downstream from the crystallization unit, or to a solids section of a combined product purification and separation unit downstream from the crystalliza- 5 tion unit, in which drying unit the obtained crystals of lithium hydroxide monohydrate can be dried.

39. The arrangement according to claim 38, wherein the drying unit includes a prod- 2019474270

uct outlet through which the final product can be recovered. 10 40. A method for recovering lithium hydroxide from a fresh feed comprising mineral raw material containing lithium, or a raw material containing lithium carbonate or a mixture of these, combined with a recycled solution and/or slurry containing lithium, wherein the method comprises 15 − pulping the feed containing lithium in the presence of water and alkali metal carbonate for producing a first slurry containing lithium, − leaching the first slurry containing lithium, optionally combined with a recy- cled solution and/or slurry, in a first leaching step at an elevated tempera- ture for producing a second slurry containing lithium carbonate, 20 − leaching the second slurry or a fraction thereof in a second leaching step in an aqueous solution containing alkali earth metal hydroxide for producing a third slurry containing lithium hydroxide, − separating the third slurry into solids that may be discarded, and a solution containing lithium hydroxide, by solid-liquid separation, 25 − recovering lithium hydroxide monohydrate by crystallising from a solution containing lithium hydroxide, and − separating a solution and/or slurry obtained during the crystallization from the process, and returning it as a recycled solution and/or slurry to one or more previous process steps including the pulping step and optionally the 30 first leaching step, o wherein at least a fraction of the solution separated from the crystalli- zation step is carried to a lithium precipitation step, wherein the solu- tion is reacted with either carbon dioxide or a mixture of carbon diox- ide and alkali metal carbonate, in order to form a lithium carbonate 35 slurry that is recycled to one or both of the pulping and first leaching steps.

41. The method according to claim 40, wherein the mineral raw material used as at 26 Feb 2026

least a part of the feed in the pulping step is a lithium-containing mineral in calcined form, preferably obtained by heat treating the raw material, more preferably by using a temperature of 900-1200°C, most suitably a temperature of 1000-1100°C. 5 42. The method according to claim 40 or claim 41, wherein the mineral raw material used in the pulping step is selected from spodumene, petalite, lepidolite, micas or clays or mixtures thereof, preferably spodumene, more preferably beta-spodumene. 2019474270

10 43. The method according to claim 40, wherein the raw material containing lithium carbonate is freshly added raw material, or is recycled from a subsequent step of the method, preferably at least a fraction from the crystallization step.

44. The method according to any one of claims 40 to 43, wherein at least a fraction 15 of the water and alkali metal carbonate carried to the pulping step is a recycled aqueous solution containing said alkali metal carbonate.

45. The method according to any one of claims 40 to 44, wherein the alkali metal carbonate used in the pulping step is selected from sodium and potassium car- 20 bonate, preferably being at least partly composed of sodium carbonate.

46. The method according to any one of claims 40 to 45, wherein the first leaching step is carried out at a temperature of 160 to 250°C, preferably at a temperature of 200 to 220°C. 25 47. The method according to any one of claims 40 to 46, wherein the first leaching step is carried out at a pressure of 10 to 30bar, preferably 15 to 25bar.

48. The method according to any one of claims 40 to 47, wherein suitable conditions 30 are achieved for the first leaching step using high-pressure steam.

49. The method according to any one of claims 40 to 48, wherein the solution is separated from the solids after the first leaching step in a separate solid-liquid sep- aration step, and the solids are carried to the second leaching step, optionally after 35 washing the solids.

50. The method according to any one of claims 40 to 49, wherein the solution is 26 Feb 2026

separated from the solids after the first leaching step, and the solution is returned to one or more of the preceding steps as a recycled solution.

5 51. The method according to any one of claims 40 to 50, wherein the solution is separated from the solids after the first leaching step, and the solution is returned as a recycled solution either to the pulping step or to the first leaching step, or a fraction to each. 2019474270

10 52. The method according to claim 51, wherein the solution is returned to the pulping step.

53. The method according to any one of claims 40 to 52, wherein the alkali earth metal hydroxide used in the second leaching step is selected from calcium and bar- 15 ium hydroxide, preferably being calcium hydroxide.

54. The method according to any one of claims 40 to 53, wherein the alkali earth metal hydroxide used in the second leaching step is mixed with water or an aqueous solution prior to addition to the second leaching step. 20 55. The method according to any one of claims 40 to 54, wherein at least a fraction of the solution separated from the solids in the solid-liquid separation of the third slurry is added to said second leaching step in the form of a recycled solution, pref- erably mixed with fresh alkali earth metal hydroxide prior to addition to the second 25 leaching step, more preferably mixed with fresh alkali earth metal hydroxide in a separate slurrying step.

56. The method according to any one of claims 40 to 55, wherein the solids obtained from the solid-liquid separation of the third slurry are washed, and preferably at least 30 a fraction of the spent washing solution is combined with the solution separated from the solids in said solid-liquid separation of the third slurry.

57. The method according to any one of claims 40 to 56, wherein the second leach- ing step is carried out at a temperature of 10-100°C, preferably 20-60°C, and most 35 suitably 20-40°C.

58. The method according to any one of claims 40 to 57, wherein the second leach- ing step is carried out at atmospheric pressure.

59. The method according to any one of claims 40 to 58, wherein a step of purifying the solution obtained from the third slurry is carried out, which step includes a puri- fication based on the purification of dissolved ions and components, preferably an 5 ion exchange or a membrane separation, or both.

60. The method according to any one of claims 40 to 59, wherein the step of purify- ing the solution obtained from the third slurry is carried out by an ion exchange, 2019474270

preferably carried out by using a cation exchange resin, particularly a selective cat- 10 ion exchange resin.

61. The method according to claim 60, wherein the ion exchange is carried out at least partly using a purification resin that has been regenerated in a separate regen- eration step, which regenerated resin typically is returned to the ion exchange. 15 62. The method according to claim 61, wherein the regeneration step is carried out using a recycled solution from a subsequent process step, preferably being the sep- arated solution obtained from the crystallization, or from a subsequent washing step.

20 63. The method according to any one of claims 40 to 59, wherein the step of purify- ing the solution obtained from the third slurry is carried out by membrane separation, whereby the membrane separation yields a purified stream, which is carried to the crystallization step, and a recycle stream, which preferably is carried to the second leaching step. 25 64. The method according to any one of claims 40 to 59, wherein the step of purify- ing the solution obtained from the third slurry is carried out by first performing a membrane separation, and by carrying the thus purified solution to an ion exchange step, for further purification. 30 65. The method according to any one of claims 40 to 64, wherein the crystallising of the lithium hydroxide monohydrate is performed by heating the solution containing lithium to a temperature of approximately the boiling point of the solution.

35 66. The method according to any one of claims 40 to 65, wherein the crystallising of the lithium hydroxide monohydrate is preceded by a pre-concentration step, prefer- ably carried out as an evaporation, for dispensing of excess liquid from the solution containing lithium.

67. The method according to any one of claims 40 to 66, wherein the crystallising of the lithium hydroxide monohydrate is performed in two or more crystallization units, preferably being sequentially arranged. 5 68. The method according to any one of claims 40 to 67, wherein the solution con- taining lithium hydroxide is mixed with one or more solutions recycled from subse- quent steps of the method before being carried to the crystallization step, or they 2019474270

are all fed separately to the crystallization step. 10 69. The method according to any one of claims 40 to 68, wherein at least a fraction of the solution separated from the crystallization step is returned to the second leaching step as a recycled solution.

15 70. The method according to any one of claims 40 to 68, wherein at least a fraction of the solution separated from the crystallization step is returned to one or both of the pulping and first leaching steps as a recycled solution.

71. The method according to any one of claims 40 to 68, wherein the lithium precip- 20 itation step is carried out as a carbonation.

72. The method according to any one of claims 40 to 68, wherein the lithium precip- itation step is carried out by reacting the solution carried to the step with carbon dioxide or a mixture of carbon dioxide and alkali metal carbonate, in order to form a 25 lithium carbonate slurry.

73. The method according to claim 71, wherein the precipitation is carried out as a carbonation, in a reaction that is left incomplete, whereby at least a trace amount of lithium hydroxide will still be present in the lithium carbonate slurry. 30 74. The method according to any one of claims 71 to 73, wherein the slurry com- prising lithium carbonate is recycled to the pulping step.

75. The method according to any one of claims 40 to 74, wherein a fraction of the 35 solution separated from the obtained crystals after the crystallization step is returned to the crystallization step as a recycled solution.

76. The method according to any one of claims 40 to 75, wherein the solids obtained 26 Feb 2026

in the crystallization step, containing crystals of lithium hydroxide monohydrate, are purified using a washing solution before recovery as the product.

5 77. The method according to claim 76, wherein the purified crystals of lithium hy- droxide monohydrate are separated from the washing solution, are dried, and there- after recovered. 2019474270

78. The method according to claim 76, wherein the spent washing solution is sepa- 10 rated from the purified crystals of lithium hydroxide monohydrate, and is returned as a recycled solution to the crystal washing step or to a step of purifying the solution separated from the third slurry or to a regeneration step preceding said purification step, or to the crystallization step, or a fraction of the spent washing solution is re- turned to two or more of these steps. 15 79. The method according to any of steps 40 to 78, which is carried out using the arrangement of any one of claims 1 to 39.

Solids

31

High Highpurity purity

hydroxide

lithium

3 Ca(OH),

Fig. 1

4 1

2 422

1 421 Na.CO3 concentrate Li Li concentrate